Lift trucks

ABSTRACT

A lift truck is adapted for narrow aisle operation by having a fixed mast mounted on the front of the truck which supports a sideways slidable frame having a top and bottom support for a pivotable mast of the lift truck. A counterbalance is provided to counteract the effect on the lift truck stability of the sideways movement of the mast.

United States Patent [191 1111 3,907,140 Jinks Sept. 23, 1975 LIFTTRUCKS 3,472,408 10/1969 Hendricks et al 214/670 Inventor: David MartinJ y, 3,820,674 6/1974 Goodacre et a1. 214/16.4 A

England FOREIGN PATENTS OR APPLICATIONS Assignee; Cleco Industries Ltd.England 1/1964 United Kingdom 1,048,228 12/1958 Germany 214/670 [22]Filed: Aug. 28, 1973 [21] Appl. No.: 392,300 Primary Examiner-Frank E.Werner Assistant ExaminerLawrence J. Oresky [30] Foreign ApplicationPriority Data Attorney, Agent, or FzrmLarson, Taylor and Hmds Aug. 31,1972 United Kingdom 40293/72 [57] ABSTRACT [52] 214/671; 212 34 A lifttruck is adapted for narrow aisle Operation by Int Cl 2 having a fixedmast mounted on the front of the truck which Supports a sidewaysSlidable frame having a top [58] Fleldof Search i ;2 9 g g and bottomsupport for a pivotable mast of the lift truck. A counterbalance isprovided to counteract the h References Cited glelcitozntgeenlgstttruckstabllity of the sldeways move UNITED STATES PATENTS 3,313,436 4/1967Mathew et al. 214/672 12 Clam, 8 W Flgures 76 8 46 \n J r 25 28 82 l 74i 4, 2 I 30 US Patent Sept. 23,1975 Sheet 1 of8 3,907,140

US Patent Sept.23,1975 Sheet2of8 3,907,140

US Patent Sept, 23,1975 Sheet 3 of8 3,907,140

US Patent Sept. 23,1975 Sheet40f8 3,907,140 I I US Patent Sept. 23,1975Sheet 5 of8 3 ,907,140

US Patent Se t.23,1975 Sheet6of8 3,907,140

US Patent Sept. 23,1975 Sheet 7 of 8 3,907,140

US Patent Sept. 23,1975 Sheet80f8 3,907,140 4 LIFT TRUCKS The inventionrelates to lift trucks and especially to lift trucks adapted for narrowaisle operation.

The invention provides a lift truck comprising a truck body, a mastfixed at the front of the truck body, a carriage extending along thefixed mast and secured to the mast at an upper position and to the mastand/or body at a lower position so as to allow the carriage to betraversed along the front of the truck body and movable mast pivotablysecured at an upper and lower position to forwardly cantilevered partsof the carriage mounting a load carriage. In operation the mast can befaced to either side of the lift truck or to the front. The fixed mastdefines an overhead guard over a drivers station on the truck body andmeans are provided to ensure that upper and lower positions of theextensible mast are traversed in unison. Conveniently the meanscomprises a shaft rotatably secured in the carriage and pinions securedto the shaft and engaging a transversely extending rack secured in afixed position with respect to the truck body adjacent the upper andlower end of the carriage. Advantageously the carriage comprises atleast two transversely spaced rollers having a vertical axis of rotationadjacent the upper end of the carriage and adjacent the lower end of thecarriage engaging in transversely extending rail members on the fixedmast and/or front of the truck body and the carriage has a roller havinga horizontal axis of rotation for engaging a transverse member on thefixed mast or lift truck body. Suitably the lift truck comprises aweight, conveniently mounted on the body which is moved to provide acounterbalance when the mast is moved to either side. Preferably aweight is provided traversible at the same time as but in an oppositedirection to the traverse of the carriage for providing a counterbalance. In one construction the weight is mounted slidably on a frontaxle of the truck body.

Preferably the carriage is connected to an arm, pivotably mounted on thefront of the truck body to traverse the carriage. Suitably the carriageis traversed by arm pivotably mounted centrally on the front of body tomove in a plane across the front which engages an upright member on thecarriage. If the arm is arranged to move through a substantial arc say158 when moving the carriage from side to side at a constant angularspeed, the speed of the carriage is reduced on approaching either sideof the lift truck. Preferably a roller is mounted on the arm engaging ina longitudinal slot in the carriage. The arm may also be connected tothe weight to provide a counterbalance to the mast.

The mast is preferably pivoted at two or more vertically spacedpositions.

The invention is more particularly described with reference to thedrawings accompanying this and the Provisional Specification in which:

FIGS. 1, 2 and 3 are a side, top and front elevation of a lift truckaccording to the invention with the mast in a position for stacking toone side;

FIG. 4 is a side view of the lift truck of FIGS. 1 to 3 with the mast ina position for stacking to the front; and

FIGS. 5, 6, 7 and 8 are a side, top, front and partial side view ofanother lift truck according to the invention.

With reference to FIGS. 1 to 4 a lift truck 2 comprises a body 4 whichsupport a carriage 6 which is cantilevered out from the body 41 and amast 8 pivoted on the forward end of the carriage 6.

The lift truck is of the counterbalanced type with the mast 8 supportedat the front and has a pair of freely rotatable non-steerable frontwheels 10 and a single driven and steerable rear wheel 12. Reartwin-drive wheels with linked steering may also be used (See FIG. 2). Abattery 14 is mounted adjacent the rear of the body 4 and a driversstation 16 is mounted near the front of the body 4. On the front of thebody 4 is mounted a frame 18 supporting the carriage in its cantileveredposition which frame comprises a rigid upright mast 20 and transversesupport 22.

The rigid mast 20 comprises; a pair of spaced posts 24 mounted on thefront of the body 4 and a pair of support members 26 which pass overheadof the drivers station 16 and are mounted directly behind it on the body4. At the top, the posts 24 are connected by a first rail 28 fortraversing the carriage 6 to absorb the forwardly directly pull of thecantilevered carriage 6.

The transverse support 22 carries a second rail 30 for traversing thecarriage absorbing horizontally directed forces and a third rail 32 forabsorbing vertically directed forces.

In between the front of the body 4 and the support 20, is mounted on afixed shaft 34 an arm 36 for moving the carriage 6 from side to side.The shaft 34 is arranged in the longitudinal direction centrally on thefront of the truck body 4. The arm 36 carries on one end a roller 38 forengaging the carriage 6. The arm 36 carries also a counterweight 40 inthe form of a seg ment of thick metal plate. The arm 36 is pivoted bymeans of a hydraulic motor which engages, aided by jockey sprockets 43,a chain 44 laid over the edge of the segmental weight 40 and secured toboth ends of the segmental weight.

The carriage 6 comprises a pair of horizontal members 46 which areconnected by a vertical tie-bar 48 and the lower one of which members isfirmly secured by support plate 50. At the rear of the upper and lowerhorizontal member 46 is provided a pair of rollers 52 engaging in therails 28 and 30 respectively. At the front of the horizontal members 46there are pivots 54 for supporting the mast 8. Underneath the lowermember 46 are mounted a pair of rollers for engaging with the rail 32and an upright member 58 which defines a channel for engaging with theroller 38 on the arm 36. Fixed to the lower part and upper part of thetraverse carriage are a pair of chains 60 and 62 which pass over rollers64, 66, 68 and 70, 72, 74 respectively which rollers are mounted on theframe 18. Movement of the upper and lower parts of the carriage arethereby synchronized.

The mast 8 is extensible and comprises inner and outer mast sections 76and 78 and a ram and chain arrangement for raising and lower forks 80supported by the inner mast section 76. A pair of transverse supportmembers 82 are fixed to the outer mast and are pivotably supported bythe pivots 54. A hydraulic rotator is mounted on the carriage 6 tocontrol the angular position of the mast 8 and rotate it aboutapproximately Guide rollers may be affixed to the side of the lift truckto enable it to pass through a narrow aisle.

In operation, the lift truck can be driven into an aisle not much widerthan the truck body 4 and the driver can pick up or deposit a load oneither side or deposit it in the aisle for another truck to pick up. Ifthe driver were to enter an aisle with the mast in the middle andpointing forwardly as in FIG. 4 and it is desired to pick up a load onthe right, the driver causes the carriage to traverse to the left whilstat the same time rotating the mast to the right to reach the positionshown in FIGS. 1 to 3. Subsequently the driver causes the carriage totraverse to the right to pick up the load.

The weight associated with the arm 36 reduces the unbalance resultingfrom the sideways displacement of the mast. The actuation of the armcauses the mast to slow down gradually in a harmonic motion whenreaching either side of the truck.

With reference to FIGS. 5 to 8, a lift truck has the same basic lay-outof the lift truck previously described. In the following only thoseparts are described in which the lift truck materially differs from theone previously described.

At the top of the rigid mast the posts are connected by a first rail 100having a central channel facing downward. The transverse support 32carries both a bottom rail 30 for absorbing horizontally directed forcesand a hardened steel flat 102 fixed to the side of the rail 30 fortaking the downward force of the extendible mast, carriage and load.

The arm 36 is not connected to a counterweight and comprises a simplearm with the roller 38 and a motor for rotating the arm 36 located bythe pivot of the arm.

The carriage has rollers suitably placed for location in or on the rails100, 30 and on the steel flat 102. The roller 106 for engaging the steelflat 102 is of hardened steel and located centrally of the roller 52located in the rail 30. The carriage has also mounted in a verticalsquare section tube 107, a vertical shaft extending between the pair ofhorizontal members and carrying pinions 109 keyed to the shaft formeshing with racks mounted on the outside of the rails 100 and 30. Inthis way the carriage is retained in a strictly vertical position as itis moved from side to side by the arm 36.

The carriage also has an extension 108 extending downward below the rail30 and connected to one endless chain guided over sprockets 110 oneither side of the truck. Connected to the chain is a weighted block 112which is slidably mounted on the front axle of the truck. The block 112is secured so that it moves in a direction opposite to that of thecarriage when it is shifted by the arm 36. A large and effectivecounterbalance can thus be achieved.

The mast 8 is rotated on the carriage 6 by means of a ram 114 mounted onthe back of the mast and having a rod with a section of rack whichengages a fixed pinion 116 on the carriage 6. Movement of the stemcauses the mast to be rotated.

In further constructions the mast can be a telescopic triple sectionmast or a non-extensible single section mast. The lift trucks may alsobe modified to make the operators station elevatable at the same time asthe load carriage to provide better supervision during loading andunloading manoeuvres. The operators station may then be mounted betweenthe posts and members 24 and 26 and may be supported by the fixed mast.

The lift trucks are capable of manipulating heavy loads safely in narrowaisles.

Reference is made to the British Patent 1,326,914 which describes andclaims a lift truck having a movable mast which is extensible andtraversible with respect to the truck, a mast fixed with respect to thetruck and a mast steady arm interconnecting upper portions of themovable mast and the fixed mast which is secured at one end of themovable mast and retained at the other end in a guide secured to thefixed mast and allowing traverse of the mast steady arm with the movablemast.

I claim:

1. A lift truck comprising a truck body, wheels supporting the truckbody, a drivers station on the truck body and a pair of transverselyspaced wheels at the front of the truck body;

a fixed mast rigidly secured to the truck body and extending upwardlythereof to a level above the drivers station, at least one uppertransversely extending member secured to the front of the fixed mastadjacent the upper part thereof above the forward field of view of thedrivers station, at least one lower transversely extending membersecured in a fixed position with respect to the truck body at the frontand adjacent the lower part of the fixed mast;

a traverse carriage extending alongside the front of the fixed mast,rigidly interconnected upper and lower means on the carriage forslidably engaging the said upper and lower transversely extendingmembers respectively, means for sliding the upper and lower meanssimultaneously from side to side of the truck body with respect to theirrespective transversely extending members, and upper and lower forwardlycantilevered members secured to the carriage at the level of the upperand lower transversely extending members respectively; a movable mastpivotably supported by the upper and lower forwardly cantileveredmembers at the level of the upper and lower transversely extendingmembers respectively and pivotable about an upright axis, means forpivoting the movable mast on the upper and lower members from a forwardfacing position to either side of the truck body and a load carriage forraising and lowering a load and supported at the front of the movablemast.

2. A lift truck as claimed in claim 1, wherein the drivers station isprovided adjacent the front of the truck body and wherein the fixed mastcomprises a plurality of upright posts secured in front of and behindthe drivers station to the truck body and interconnected at the top todefine thereby an overhead guard.

3. Lift truck as claimed in claim 1 in which a chain is providedinterconnecting the carriage and the fixed mast to cause upper and lowerparts of the carriage to move sideways in unison.

4. Lift truck as claimed in claim 1 in which a rack is associated witheach of the transversely extending members and an upright shaft isrotatably mounted in the carriage and pinions are keyed to upper andlower parts of the shaft for engaging the racks and traversing upper andlower parts of the carriage in unison.

5. Lift truck according to claim 1, wherein the means for slidablyengaging the transversely extending members comprises a pair oftransversely spaced rollers having a vertical axis of rotation and thetransversely extending members comprise members having a U- shapedsection for receiving the rollers.

6. Lift truck according to claim 5 wherein the means for slidablyengaging the transversely extending members comprises a roller having ahorizontal axis of rotation and the transversely extending memberscomprise a flat mounted adjacent the lower part of the fixed mast forsupporting said roller edgeways. I

7. Lift truck according to claim 1 in which a weight is mounted adjacentthe front of the truck body and means are provided for moving thatweight transversely at the same time as, but in an opposite directionto, the carriage to thereby provide a counter balance.

8. Lift truck as claimed in claim 7 in which a shaft is providedextending between the transversely spaced wheels at the front of thetruck body, the weight is mounted slidably on said shaft and a chain isprovided interconnecting the weight and the carriage.

9. Lift truck as claimed in claim 1 in which the means for sliding thecarriage from side to side comprise an arm pivotably along asubstantially horizontal axis and mounted at the front of the truckbody, a roller secured to the arm and an upright slot in the carriagefor engaging the roller on the arm.

10. Lift truck comprising a truck body, wheels supporting the truck bodyand including a pair of transversely spaced wheels at the front of thetruck body, said pair of wheels being interconnected by a shaft, adrivers station adjacent the front of the truck body;

a fixed mast having upright posts secured in front of and behind thedrivers station to the truck body and interconnected at the top to apair of transversely spaced posts being provided in front of the driversstation, a transversely extending U- sectioned member secured adjacentthe top to said pair of posts, a transversely extending U-sectionedmember secured adjacent the bottom of said pair of posts, a transverselyextending steel flat secured adjacent the latter U-sectioned member;

a traverse carriage extending alongside the front of the truck body andthe front of the fixed mast, a pair of transversely spaced rollersrotatably mounted on vertical centres at an upper part of the carriageand received in the U-sectioned member adjacent the top of the posts, apair of further transversely spaced rollers rotatably mounted onvertical centres at a lower part of the carriage and received in theU-sectioned member adjacent the bottom of the posts, a single rollermounted on the carriage rotatable on a horizontal centre for bearingedgeways on top of the steel flat;

an arm pivotable along a substantially horizontal axis and mounted atthe front of the truck body, a roller secured to the arm and an uprightslot in the carriage for engaging the roller on the arm to therebyenable the carriage to be moved from side to side of the truck body;

upper and lower forwardly cantilevered members secured to the carriage;

a movable mast pivotably supported by the upper and lower members, meansfor pivotting the mast on the upper and lower members and a loadcarriage for raising and lowering a load supported at the front of themovable mast, whereby the load carriage can be turned to the front or toeither side of the truck body.

11. Lift truck according to claim 10, further comprising a weightslidably mounted on the shaft interconnecting the front wheels and achain interconnecting the weight and the traverse carriage to cause theweight to be slid sideways in a direction opposite to the carriage tocounteract the effect of a sideways shift of a load on the movable mast.

12. Lift truck according to claim 1 wherein said means for sliding theupper and lower means comprises a drive means for sliding the carriagefrom side to side of the truck and a means mounted on the upper andlower means for synchronizing the sliding movement thereof with respectto the corresponding upper and lower transversely extending members.

1. A lift truck comprising a truck body, wheels supporting the truckbody, a driver''s station on the truck body and a pair of transverselyspaced wheels at the front of the truck body; a fixed mast rigidlysecured to the truck body and extending upwardly thereof to a levelabove the driver''s station, at least one upper transversely extendingmember secured to the front of the fixed mast adjacent the upper partthereof above the forward Field of view of the driver''s station, atleast one lower transversely extending member secured in a fixedposition with respect to the truck body at the front and adjacent thelower part of the fixed mast; a traverse carriage extending alongsidethe front of the fixed mast, rigidly interconnected upper and lowermeans on the carriage for slidably engaging the said upper and lowertransversely extending members respectively, means for sliding the upperand lower means simultaneously from side to side of the truck body withrespect to their respective transversely extending members, and upperand lower forwardly cantilevered members secured to the carriage at thelevel of the upper and lower transversely extending membersrespectively; a movable mast pivotably supported by the upper and lowerforwardly cantilevered members at the level of the upper and lowertransversely extending members respectively and pivotable about anupright axis, means for pivoting the movable mast on the upper and lowermembers from a forward facing position 90* to either side of the truckbody and a load carriage for raising and lowering a load and supportedat the front of the movable mast.
 2. A lift truck as claimed in claim 1,wherein the driver''s station is provided adjacent the front of thetruck body and wherein the fixed mast comprises a plurality of uprightposts secured in front of and behind the driver''s station to the truckbody and interconnected at the top to define thereby an overhead guard.3. Lift truck as claimed in claim 1 in which a chain is providedinterconnecting the carriage and the fixed mast to cause upper and lowerparts of the carriage to move sideways in unison.
 4. Lift truck asclaimed in claim 1 in which a rack is associated with each of thetransversely extending members and an upright shaft is rotatably mountedin the carriage and pinions are keyed to upper and lower parts of theshaft for engaging the racks and traversing upper and lower parts of thecarriage in unison.
 5. Lift truck according to claim 1, wherein themeans for slidably engaging the transversely extending members comprisesa pair of transversely spaced rollers having a vertical axis of rotationand the transversely extending members comprise members having aU-shaped section for receiving the rollers.
 6. Lift truck according toclaim 5 wherein the means for slidably engaging the transverselyextending members comprises a roller having a horizontal axis ofrotation and the transversely extending members comprise a flat mountedadjacent the lower part of the fixed mast for supporting said rolleredgeways.
 7. Lift truck according to claim 1 in which a weight ismounted adjacent the front of the truck body and means are provided formoving that weight transversely at the same time as, but in an oppositedirection to, the carriage to thereby provide a counter balance.
 8. Lifttruck as claimed in claim 7 in which a shaft is provided extendingbetween the transversely spaced wheels at the front of the truck body,the weight is mounted slidably on said shaft and a chain is providedinterconnecting the weight and the carriage.
 9. Lift truck as claimed inclaim 1 in which the means for sliding the carriage from side to sidecomprise an arm pivotably along a substantially horizontal axis andmounted at the front of the truck body, a roller secured to the arm andan upright slot in the carriage for engaging the roller on the arm. 10.Lift truck comprising a truck body, wheels supporting the truck body andincluding a pair of transversely spaced wheels at the front of the truckbody, said pair of wheels being interconnected by a shaft, a driver''sstation adjacent the front of the truck body; a fixed mast havingupright posts secured in front of and behind the driver''s station tothe truck body and interconnected at the top to a pair of transverselyspaced posts being provided in front of the driver''s station, atransversely extending U-sectioneD member secured adjacent the top tosaid pair of posts, a transversely extending U-sectioned member securedadjacent the bottom of said pair of posts, a transversely extendingsteel flat secured adjacent the latter U-sectioned member; a traversecarriage extending alongside the front of the truck body and the frontof the fixed mast, a pair of transversely spaced rollers rotatablymounted on vertical centres at an upper part of the carriage andreceived in the U-sectioned member adjacent the top of the posts, a pairof further transversely spaced rollers rotatably mounted on verticalcentres at a lower part of the carriage and received in the U-sectionedmember adjacent the bottom of the posts, a single roller mounted on thecarriage rotatable on a horizontal centre for bearing edgeways on top ofthe steel flat; an arm pivotable along a substantially horizontal axisand mounted at the front of the truck body, a roller secured to the armand an upright slot in the carriage for engaging the roller on the armto thereby enable the carriage to be moved from side to side of thetruck body; upper and lower forwardly cantilevered members secured tothe carriage; a movable mast pivotably supported by the upper and lowermembers, means for pivotting the mast on the upper and lower members anda load carriage for raising and lowering a load supported at the frontof the movable mast, whereby the load carriage can be turned to thefront or to either side of the truck body.
 11. Lift truck according toclaim 10, further comprising a weight slidably mounted on the shaftinterconnecting the front wheels and a chain interconnecting the weightand the traverse carriage to cause the weight to be slid sideways in adirection opposite to the carriage to counteract the effect of asideways shift of a load on the movable mast.
 12. Lift truck accordingto claim 1 wherein said means for sliding the upper and lower meanscomprises a drive means for sliding the carriage from side to side ofthe truck and a means mounted on the upper and lower means forsynchronizing the sliding movement thereof with respect to thecorresponding upper and lower transversely extending members.